New Zealand's newest lake has burst its dam but the feared catastrophic collapse now seems less likely.
Officials have been keeping a nervous watch on the 2.5km lake in the Mt Aspiring National Park amid fears the dam created by a landslip would collapse, sending thousands of cubic metres of water gushing down the Young Valley.
The lake over-topped the dam about 8pm on Friday sending a flow of water down the valley but there had been no catastrophic collapse.
But Department of Conservation (DoC) spokesman John Gordon says the dam appeared to be holding yesterday, after engineers and geologists flew over the lake to discover a V-shaped channel, 4-5m wide, had been carved into the dam.
"The dam looks reasonably strong at the moment... but time will tell," he said.
DoC consultant geologist Jeff Bryant, who inspected the dam yesterday along with staff from the Otago Regional Council and the Queenstown Lakes District Council, says water is "piping" through the bottom of the landslip and there are holes appearing above the seepage, but so far the integrity of the dam remained uncompromised.
The lake was made when a massive landslide slammed into the north branch of the Young River, near the head of Lake Wanaka. It created a dam 70m high, only 3km above the confluence with the south branch, which flows into the Makarora River.
Farmers with low-lying paddocks were told to move stock and machinery as rain pushed the water level up and officials warned the lake was likely to over-top the dam.
Farm managers Mike and Lorraine King, who live in the only property considered at risk of flooding, moved out of their home on the Lonestar Mt Albert Station on Friday and sought refuge in nearby Makarora, where about 80 people live.
The owner of the station, American Tom Sturgess, claims DoC hasn't done enough to prevent a catastrophic failure of the dam and says he will hold the department financially responsible for any damage to his farm.
On Friday night one of two monitoring radios in the overflow's expected path stopped transmitting, raising fears a collapse had occurred. Transit New Zealand and DoC staff, along with volunteers, manned checkpoints at either end of the valley throughout Friday night to warn motorists not to leave the road or stop unnecessarily.
But the transmission failure turned out to be caused by a flat battery. The battery was replaced yesterday and the twin radio warning system remains in place. Makarora residents have a listening watch roster of the radios. If one or both stop transmitting, that should indicate a sudden release of water.
And in Makarora, residents are putting a positive spin on the situation. Makarora Valley Association chairman Devon Miller says the makeshift lake has put the small township on the map and drawn lots of visitors to the area.
Helicopters were constantly buzzing over the area, taking sightseers over the lake. "We've become the centre of the universe, whether we like it or not," Miller says.
Residents in the town are unfazed by the attention and life is continuing as normal for Makarora locals: "We live in a dynamic part of the country so we're used to things happening."
- Sunday Star Times
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